JPS6233801B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for an electric vehicle using a chopper using a thyristor, and particularly to an electric vehicle control device that allows safe operation even when the alternating current voltage for gate control drops.

In recent electric vehicle control devices, chopper control using power thyristors is often used.
The gate control circuit of the thyristor often uses semiconductors such as transistors and integrated circuits to perform high-speed and precise gate control. Generally, alternating current is used as a power source for gate control circuits because it requires insulation from other control circuits and multiple voltages.

If the alternating current voltage that is the power source for the gate control drops, the control logic sequence made up of semiconductors will be disrupted, and there is a risk that an overcurrent or overvoltage accident will occur that can lead to failure of the main circuit equipment. Furthermore, the power of the gate pulse for igniting the gate of the thyristor is insufficient, resulting in an incomplete pulse, which may cause the thyristor to break down.

In order to prevent the above-mentioned problems, in the conventional technology, an AC voltage detector is installed, and when the AC voltage drops due to some reason, the main circuit is disconnected, and the main circuit disconnector is opened. Therefore, a method was adopted in which the gate signal of the thyristor was stopped. In the above control method, it takes about 100 ms from detecting a drop in the AC voltage until the main circuit is opened, and during this time the chopper operation is repeated (the number of operations determined by the chopper frequency, for example, the chopper frequency However, at 200 Hz, there is no protection against the on-off operation being performed 20 times in 100 ms), and the device is completely defenseless against the above-mentioned problems that occur during this period. As a main circuit for an electric vehicle using a chipper using a thyristor, the one shown in FIG. 1 is well known. In FIG. 1, the filter capacitor FC is charged from the overhead contact line TW via the current collector P, the breaker L, and the filter reactor FL, and the main motor M is energized. The energizing power of the main motor is controlled on/off by the CH via the main smoothing reactor MSL.

Note that DF is a freewheel diode,
DCCT is a direct current detector.

Figure 2 (block diagram) shows an example of a circuit mainly consisting of a power supply section for gate control that controls on/off of the chopper CH. In Figure 2, AC power from an auxiliary power supply installed on the vehicle is isolated from the main circuit by a transformer T, divided into the necessary voltages, and sent to the control logic unit GL via the voltage regulator AVR. The output of the control logic device GL is supplied as a control signal to the gates of the main thyristor MTh and the auxiliary thyristor ATh, respectively, to control on/off of each of the thyristors.

The secondary side AC voltage of the transformer T, that is, the AC input voltage of the on/off control circuit of the thyristors MTh and ATh, is detected by the voltage detector VD, and when the value falls below a specified value, Ya disconnector L
(See Figure 1) The control coil (not shown) is demagnetized and the main circuit is cut off. When the breaker L opens, the control signals for the gates of both thyristors MTh and ATh are stopped. The reason why the gate signal is continued until after the breaker is opened is that if the gate signal is stopped while the breaker L is turned on, the current that was flowing from the power supply to the traction motor M side will flow through the filter. This is because the voltage will flow only into the capacitor FC, causing an overvoltage in the capacitor FC, which will cause problems such as destroying the thyristor of the chopper CH.
Now, as mentioned above, there is a time delay of about 100 ms from when the voltage detector VD operates until the main circuit is opened, and an example of the voltage attenuation characteristic during this time is shown in FIG. Also, the relationship between the pulse width at the maximum conduction rate and the pulse width at the minimum conduction rate is
It is shown in Figure 4. The upper part of FIG. 4 shows the pulse width Tx within the chopper period T at the maximum conduction rate, and the lower part shows the pulse width Tm at the minimum conduction rate. For convenience, the pulse width is expressed as a chopping period T.
If the value obtained by dividing Tx and Tm is taken as the respective conduction rate, as is clear from Fig. 4, the minimum conduction rate is approximately 0.1, and the maximum conduction rate is approximately 0.9~0.
It becomes 0.92. In this way, the reason why the on-gate signal is continued to be applied to the main thyristor MTh during the on-period of the tipper is to prevent misfiring and erroneous extinguishing of the main thyristor, and continuous pulses may be continued during the on-period. This is well known.
Here, if the peak value VG of the on-pulse output voltage is constant, the power consumption of the power supply of the gate control device at the maximum conduction rate is approximately nine times that at the minimum conduction rate. Therefore, the voltage attenuation characteristic becomes steep. This state is shown in FIG. In other words, the control voltage of the voltage attenuation characteristic f(Tx) at the maximum conduction rate
The attenuation rate of VC is the voltage attenuation characteristic f at the minimum conduction rate.
The slope is steeper than that of (Tm). On the other hand, as shown in Figure 5, according to the voltage attenuation characteristic f (Tm) when the conduction rate is minimum, the above-mentioned time delay is about 100
In the period of ms, the control voltage VC is the permissible lower limit voltage.
Control is performed without any problem at voltages above VCa, but when the conduction rate is at its maximum, the control voltage VC falls below the allowable lower limit voltage VCa within a time delay period of about 100 ms, causing malfunction of the control logic device or incomplete pulses. ,
The drawback was that the thyristor was destroyed before the main circuit was cut off.

An object of the present invention is to eliminate the drawbacks of the prior art described above, and to reduce the overvoltage that occurs in an electric vehicle using a chopper using a thyristor until the main circuit is suddenly disconnected when the gate control AC voltage drops. An object of the present invention is to provide an electric vehicle control device that prevents the destruction of a thyristor and enables safe driving.

The electric vehicle control device of the present invention, in an electric vehicle using a chopper using a thyristor, determines the conduction rate of the thyristor by the output of an AC voltage detector for gate control. This electric vehicle control device is characterized in that it is provided with means for setting the control signal pulse width divided by the control signal pulse width to a predetermined small value.

That is, it detects a voltage drop in the power supply of the gate control device, gives an opening command to the main circuit circuit breaker, and gives a command to the gate control device to narrow down the on-gate time width of its output gate signal. As a result, it takes about 100ms until the breaker actually opens.
During this period, the power consumed by the power supply of the gate control device is suppressed and its voltage drop is delayed. For this reason,
For approximately 100ms until the breaker opens, the power supply voltage for the gate control device to operate normally can be maintained, eliminating the risk of thyristor destruction due to malfunction of the control logic or generation of incomplete pulses. can significantly reduce the risk of damage.

An embodiment of the electric vehicle control device of the present invention will be described with reference to FIG. In FIG. 3, PD is a pattern generation section which generates a pattern voltage VP corresponding to a power running notch or brake notch command from the driver's cab, and the pattern voltage VP is supplied to an operational amplifier section OP. Tr is a transistor, and its load circuit (collector-emitter circuit) is connected to the output circuit of the pattern generator PD via a resistor R, and the output of the voltage detector VD is supplied to the base of the transistor Tr, which will be described in detail later. However, when the AC voltage drops below the specified value, the pattern voltage VP is clamped to the minimum. FD is a main circuit current converter that converts the main circuit current detected by the main circuit current detector DCCT into a predetermined feedback voltage VF, and the feedback voltage VF is supplied to the operational amplifier OP. The output of the operational amplifier section OP is supplied to the gate pulse generation section GP for the main thyristor MTh via the phase shift control section PS, and the pulse output from the gate pulse generation section GP is
VG controls on/off of the main thyristor MTh.

To explain the operation of the embodiment of the present invention shown in FIG. 3, when the AC voltage is normal, the voltage detector
Since the output of VD is off, the transistor Tr is also off. Therefore, the pattern generation section PD outputs a pattern voltage VP corresponding to the notch command from the driver's cab, and this output is supplied as is to the operational amplifier section OP. In the operational amplifier OP, a calculation is performed between the pattern voltage VP and the feedback voltage VF, and the output that is the difference between them is output to the phase shift control section PS, and the output of the phase shift control section PS is supplied to the gate pulse generation section GP. The on/off control of the main thyristor MTh, that is, the conduction rate, is controlled from the minimum to the maximum by the gate pulse width from the gate pulse generator GP.

When the AC voltage drops for some reason, the voltage detector VD operates, the transistor Tr turns on, and the pattern voltage VP is clamped to the preset minimum value via the resistor R. As a result, the pulse width of the main thyristor MTh is narrowed down to the minimum value, that is, the minimum conduction rate. Therefore, the time from the time the voltage detector VD starts operating until the main circuit is finally disconnected is approximately
Since it is possible to minimize the power consumed during 100ms and minimize voltage attenuation, overcurrent and overvoltage due to malfunction of control logic caused by sudden voltage attenuation can be minimized. ,
Thyristor breakdown due to incomplete gate pulses can be prevented. In the embodiment of the present invention shown in FIG. 3, a method was described in which the pattern voltage was clamped as a means to reduce the conduction rate, but the same effect can be obtained by clamping the output of the phase shift control section. It will be done.

As is clear from the above description, according to the present invention, in the electric vehicle control device using a chopper using a thyristor, the AC voltage detector operates when the gate control AC voltage falls below a specified value. It is possible to minimize the attenuation of the control voltage during the approximately 100 ms period from when the main circuit is opened until the main circuit is opened, preventing damage to the thyristor and ensuring safe operation.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing an example of the main circuit of an electric car using a chipper using a well-known thyristor, and Figure 2 mainly shows the gate control power supply section of the chipper thyristor shown in Figure 1. 3 is a block diagram showing an example of the gate control circuit of the electric vehicle control device of the present invention, and FIG. 4 shows the conduction rate and control pulse of the thyristor for the chopper. A control pulse waveform diagram showing the relationship with width. Figure 5 shows the control voltage attenuation characteristics after the voltage detector of the gate control AC power supply operates, and the control voltage attenuation characteristics shown in the cases of maximum and minimum conduction ratios. It is a diagram. CH...Thyristor stopper, DCCT...Main circuit current detection unit, VD...Voltage detector, AVR...Voltage regulator, GL...Control logic device, MTh...Main thyristor, ATh...Auxiliary thyristor, PD...Pattern generation section, VP...Pattern voltage, FD...Main circuit current conversion section, VF...Feedback voltage, OP...
…Operation amplifier unit, PS…Phase shift control unit, GP…Gate pulse generation unit, VG…Pulse output, Tr…Transistor, R…Resistance.

Claims (1)

[Claims] 1. A thyristor chopper that controls the voltage supplied to the traction motor via an overhead line disconnector, a gate control device that provides a gate signal to this chopper that continues during its on period, and a power supply voltage for this gate control device. and protection means for issuing an opening command to the shield breaker in response to the output of the voltage drop detection means, wherein the gate control is performed in response to the output of the voltage drop detection means. 1. An electric vehicle control device comprising means for acting on the device to narrow down the conduction rate of a gate output signal.